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United States Patent |
6,174,919
|
Hickey
|
January 16, 2001
|
Cyanoacrylate compositions with vinyl terminated ester groups
Abstract
An adhesive composition includes compounds having the following formula:
##STR1##
wherein R.sub.1 is alkyl, alkoxy alkyl, anhydride, ether, ester, or amide,
and R.sub.2 and R.sub.3 are hydrogen, alkyl, alkoxy alkyl, hydroxy,
alkenyl, ester, carboxylic acid or ether and wherein R.sub.1 is optionally
omitted where R.sub.2 and R.sub.3 are not both hydrogen.
Inventors:
|
Hickey; Timothy P. (Raleigh, NC)
|
Assignee:
|
Closure Medical Corporation (Raleigh, NC)
|
Appl. No.:
|
025473 |
Filed:
|
February 18, 1998 |
Current U.S. Class: |
514/519; 156/326; 156/330.9; 424/400; 424/443; 424/448; 424/487 |
Intern'l Class: |
A01N 037/34 |
Field of Search: |
424/400,443,448,487
156/330.9,326
|
References Cited
U.S. Patent Documents
2721858 | Oct., 1955 | Joyner et al.
| |
3254111 | May., 1966 | Hawkins et al.
| |
3554990 | Jan., 1971 | Quinn et al.
| |
3940362 | Feb., 1976 | Overhults.
| |
3975422 | Aug., 1976 | Buck.
| |
3995641 | Dec., 1976 | Kronenthal et al.
| |
4041062 | Aug., 1977 | Buck.
| |
4127382 | Nov., 1978 | Perry.
| |
4134929 | Jan., 1979 | Stoakley et al.
| |
4136138 | Jan., 1979 | Dombroski et al.
| |
4364876 | Dec., 1982 | Kimura et al.
| |
4720513 | Jan., 1988 | Kameyama et al. | 523/203.
|
5259835 | Nov., 1993 | Clark et al.
| |
5328687 | Jul., 1994 | Leung et al.
| |
5480935 | Jan., 1996 | Greff et al. | 524/776.
|
5514371 | May., 1996 | Leung et al.
| |
5514372 | May., 1996 | Leung et al.
| |
5575997 | Nov., 1996 | Leung et al.
| |
5582834 | Dec., 1996 | Leung et al.
| |
5624669 | Apr., 1997 | Leung et al.
| |
Foreign Patent Documents |
1527561 | Oct., 1978 | GB.
| |
WO 97/31598 | Sep., 1997 | WO.
| |
Primary Examiner: Page; Thurman K.
Assistant Examiner: Kulkosky; P.
Attorney, Agent or Firm: Oliff & Berridge, PLC
Claims
What is claimed is:
1. An adhesive composition with improved properties of chemical durability,
flexibility and elasticity of resulting polymers and copolymers,
comprising a compound of the following formula (I):
##STR7##
wherein R.sub.1 is selected from the group consisting of alkyl having at
least 2 carbon atoms, alkoxy, anhydride, ether, ester, and amide, wherein
R.sub.2 and R.sub.3 are independently selected from the group consisting
of hydrogen, alkyl, alkoxy, hydroxy, alkenyl, ester, carboxylic acid,
ether and electron withdrawing groups, and
wherein R.sub.1 may also optionally be omitted or be an alkyl having 1
carbon atom when R.sub.2 and R.sub.3 are not both hydrogen.
2. The adhesive composition according to claim 1, wherein said electron
withdrawing groups are selected from the group consisting of halogens,
amides, cyanos, esters, acids and ethers.
3. The adhesive composition according to claim 1, wherein R.sub.1 is an
alkyl having from about 2 to 8 carbon atoms.
4. The adhesive composition according to claim 1, wherein R.sub.2 and
R.sub.3 are hydrogen.
5. The adhesive composition according to claim 1, wherein R.sub.2 and
R.sub.3 are alkyls having from 1 to 3 carbon atoms.
6. The adhesive composition according to claim 1, further comprising an
initiator.
7. The adhesive composition according to claim 6, wherein said initiator is
selected from the group consisting of benzalkonium chloride, stannous
octoate and sodium tetradecyl sulfate.
8. The adhesive composition according to claim 1, further comprising a
radical initiator.
9. The adhesive composition according to claim 8, wherein said radical
initiator is selected from the group consisting of di-t-butyl peroxide,
azobisisobutyronitrile and benzoylperoxide.
10. A method of joining together surfaces, comprising:
(a) holding together at least two surfaces to form abutted surfaces, and
(b) applying across said abutted surfaces an adhesive composition according
to claim 1.
11. An adhesive composition comprising a homopolymer of the compound of
claim 1.
12. An adhesive composition comprising a copolymer of the compound of claim
1 and a 1,1-disubstituted ethylene monomer.
13. The adhesive composition according to claim 12, wherein said ethylene
monomer is n-butyl cyanoacrylate or 2-octyl cyanoacrylate.
14. The adhesive composition according to claim 1, wherein crosslinking
occurs through the vinyl terminated ester group.
15. The adhesive composition according to claim 1, further comprising an
ultraviolet initiator.
16. A method of treatment comprising using the adhesive composition of
claim 1 in a biomedical application selected from the group consisting of
drug delivery, burn treatment, setting fractured bone structures,
retarding blood flow from wounds, aiding repair and regrowth of living
tissue and apposing surgically incised or traumatically lacerated internal
or external tissues.
17. The adhesive composition according to claim 1, further comprising at
least one acidic stabilizing agent.
18. The adhesive composition according to claim 17, further comprising at
least one radical stabilizing agent.
19. The adhesive composition according to claim 18, further comprising at
least one plasticizing agent.
Description
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention is directed to monomer compositions useful to form
industrial, consumer or medical adhesives and sealants, and methods of
applying such compositions. More particularly, this invention relates to
monomeric cyanoacrylate compositions having vinyl terminated ester groups
that allow a biologically acceptable method of cross-linking through the
vinyl group.
2. Description of Related Art
U.S. Pat. No. 5,624,669 to Leung et al., discloses hemostatic procedures
for sealing punctures and incisions in blood vessels and internal organs
by applying a cyanoacrylate monomer. Although the cyanoacrylate may
polymerize and/or cross-link in vivo, it preferably does so without the
need for external sources of physical initiation such as irradiation.
U.S. Pat. No. 4,134,929 to Stoakley et al. discloses a polymerizable
monomeric allyl 2-cyanoacrylate containing portion comprising an amount of
an organic peroxide free radical providing compound sufficient to cause
crosslinking of a difunctional monomer diester with the allyl
2-cyanoacrylate. Stoakley discloses that crosslinking may occur by way of
the allyl group.
U.S. Pat. No. 4,136,138 to Dombroski et al. discloses a polymerizable
monomeric 2-cyanoacrylate containing portion comprising an amount of an
organic peroxide free radical providing compound sufficient to cause
crosslinking of a difunctional monomer diester with the 2-cyanoacrylate.
Dombroski discloses that the allyl 2-cyanoacrylate-based adhesive
compositions are especially useful as dental adhesives.
U.S. Pat. No. 3,975,422 to Buck discloses difunctional monomers where R is
an organic linking group derived from a diol or a dihalide of the formula
X--R--X, where X is either Cl, Br, I, or hydroxy. The difunctional
monomers are employed as crosslinking agents for monofunctional esters of
2-cyanoacrylates. The monofunctional cyanoacrylate monomers may be
cyanoacrylates that are terminated by an alkyl, cyclohexyl or phenyl
group. Copolymerized compositions of the monomer blends (difunctional and
monofunctional) are useful as adhesives in dental applications. The
polymerization of these compositions is initiated by an anionic catalyst
or by thermal or other means.
SUMMARY OF THE INVENTION
The present invention is directed to monomeric cyanoacrylate compositions
having vinyl terminated ester groups that cross-link through the vinyl
group, and biomedical uses of such compositions. Cross-linking occurs by
way of the vinyl terminated ester groups. In embodiments, chemical
durability, flexibility and elasticity of the resulting polymers or
copolymers may be increased and degradability can be reduced. In addition,
in embodiments high temperatures or ultraviolet initiators may not be
needed for cross-linking.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Cyanoacrylate adhesive compositions of the invention contain compounds
represented by the following formula (I):
##STR2##
wherein R.sub.1 is alkyl, alkoxy, anhydride, ether, ester, or amide, and
R.sub.2 and R.sub.3 are independently alkyl, alkoxy, hydrogen, hydroxy,
alkenyl, ester, carboxylic acid, ether, or electron withdrawing groups
such as halogens, amides, cyanos, esters, acids and ethers. Preferably,
R.sub.1 is an alkyl having from about 1 to 8 carbon atoms. Preferably,
R.sub.2 and R.sub.3 are hydrogen atoms. More preferably, R.sub.2 and
R.sub.3 are alkyl groups having from about 1 to 3 carbon atoms. The
R.sub.1 group extends the distance of the R.sub.2 and R.sub.3 groups away
from the carbonyl group, thereby making them more chemically accessible
and improving chemical durability, flexibility and elasticity of a polymer
comprising the monomer. In embodiments, R.sub.1 may be omitted if R.sub.2
and R.sub.3 are not both hydrogen.
In embodiments, the adhesive compositions may additionally contain heat
and/or light (e.g., visible or ultraviolet light) activated initiators and
accelerators that initiate cross-linking of the cyanoacrylate compounds.
Particular initiators for particular systems may be readily selected by one
of ordinary skill in the art without undue experimentation. Suitable
polymerization initiators for the cyanoacrylate compositions include, but
are not limited to, detergent compositions; surfactants: e.g., nonionic
surfactants such as polysorbate 20 (e.g., Tween 20.TM.), polysorbate 80
(e.g., Tween 80.TM.) and poloxamers, cationic surfactants such as
tetrabutylammonium bromide, anionic surfactants such as benzalkonium
chloride or its pure components, stannous octoate (tin (II)
2-ethylheaxanoate), and sodium tetradecyl sulfate, and amphoteric or
zwitterionic surfactants such as dodecyldimethyl(3-sulfopropyl)ammonium
hydroxide, inner salt; amines, imines and amides, such as imidazole,
tryptamine, urea, arginine and povidine; phosphines, phosphites and
phosphonium salts, such as triphenylphosphine and triethyl phosphite;
alcohols such as ethylene glycol, methyl gallate, ascorbic acid, tannins
and tannic acid; inorganic bases and salts, such as sodium bisulfite,
magnesium hydroxide, calcium sulfate and sodium silicate; sulfur compounds
such as thiourea and polysulfides; polymeric cyclic ethers such as
monensin, nonactin, crown ethers, calixarenes and polymeric epoxides;
cyclic and acyclic carbonates, such as diethyl carbonate; phase transfer
catalysts such as Aliquat 336; and organometallics such as cobalt
naphthenate and manganese acetylacetonate and radical initiators.
Suitable initiators for both of the polymerization of the cyanoacrylate and
cross-linking of the vinyl group of the composition include, but are not
limited to, radicals, such as di-t-butyl peroxide, azobisisobutyronitrile
and benzoylperoxide and sodium bisulfite. The polymerizable and/or
cross-linkable material may also contain an initiator which is inactive
until activated by a catalyst or accelerator (included within the scope of
the term "initiator" as used herein). Accelerators for radical initiators
such as dimethylaminopyridine and other aminopyridine type molecules may
act as an initiator for the cyanoacrylate as well as for the radical
polymerization of the vinyl moiety.
In embodiments, when R.sub.1 is omitted and R.sub.2 and/or R.sub.3 are a
moiety other than hydrogen, and the composition is to be cationically
polymerizable, materials such as strong acids, alkyl iodides
(iodomethane), iodine, acetyl perchlorate, and Lewis acids (boron
trifluoride, tin tetrachloride, aluminum trichloride, and organometallic
derivatives, e.g., RAlCl.sub.2, R.sub.2 AlCl, wherein R is an alkyl group
and R.sub.2 is two R groups) may be used.
The monomer compositions of the present invention and polymers formed
therefrom are useful as tissue adhesives, sealants for preventing bleeding
or for covering open wounds, and in other biomedical applications. They
find uses in, for example, apposing surgically incised or traumatically
lacerated internal and/or external tissues; setting fractured bone
structures; retarding blood flow from wounds; drug delivery; dressing
burns; and aiding repair and regrowth of living tissue.
Conventional surgical adhesive compositions have included plasticizers with
the adverse effect of reducing the film strength. It has been discovered
that, contrary to prior belief, the film strength (e.g., toughness) under
certain conditions is not adversely reduced upon the addition of greater
amounts of plasticizing agent. Depending on the particular acidic
stabilizing agent and the purity of the monomer utilized in the adhesive
composition, the addition of greater amounts of plasticizing agent may
increase the toughness of the resulting bond formed on the wound. Acidic
stabilizing agents do not significantly affect the polymerization of the
monomer in the present composition and provide increased film strength
with increasing amounts of plasticizing agents.
Monomers that may be used in this invention are polymerizable, e.g.
anionically polymerizable or free radical polymerizable, to form polymers.
In embodiments, the cyanoacrylate composition may comprise a homopolymer
of the monomer of formula (I) or a copolymer or terpolymer with other
monomers. Such other monomers include, but are not limited to, acrylate
monomers, methacrylate monomers, and 1,1-disubstituted ethylene monomers
of the formula:
HRC.dbd.CXY (II)
wherein X and Y are each strong electron withdrawing groups, and R is H,
--CH.dbd.CH.sub.2, or an alkyl such as methyl, ethyl and other lower
alkyls such as butyl and the like, provided that X and Y are both cyano
groups, a C.sub.1 -C.sub.4 alkyl group.
Examples of monomers within the scope of formula (II) include
alpha-cyanoacrylates, vinylidene cyanides, C.sub.1 -C.sub.4 alkyl
homologues of vinylidene cyanides, dialkyl methylene malonates,
acylacrylonitriles, vinyl sulfinates and vinyl sulfonates of the formula
H.sub.2 C.dbd.CX'Y' wherein X' is --SO.sub.2 R' or --SO.sub.3 R' and Y' is
--CN, --COOR', --COCH.sub.3, --SO.sub.2 R' or --SO.sub.3 R', and R' is H
or hydrocarbyl.
Preferred monomers of formula (II) for use in this invention are
alpha-cyanoacrylates. These monomers are known in the art and have the
formula
##STR3##
wherein R.sup.2 is hydrogen or lower alkyl and R.sup.3 is a hydrocarbyl or
substituted hydrocarbyl group including polymeric groups; a group having
the formula --R.sup.4 --O--R.sup.5 --O--R.sup.6, wherein R.sup.4 is a
1,2-alkylene group having 2-4 carbon atoms, R.sup.5 is an alkylene group
having 2-4 carbon atoms, and R.sup.6 is an alkyl group having 1-6 carbon
atoms; or a group
##STR4##
wherein n is 1-10, preferably 1-5 carbon atoms and R.sup.8 is an organic
moiety.
Examples of suitable hydrocarbyl and substituted hydrocarbyl groups include
straight chain or branched chain alkyl groups having 1-16 carbon atoms;
straight chain or branched chain C.sub.1 -C.sub.16 alkyl groups
substituted with an acyloxy group, a haloalkyl group, an alkoxy group, a
halogen atom, a cyano group, or a haloalkyl group; straight chain or
branched chain alkenyl groups having 2 to 16 carbon atoms; straight chain
or branched chain alkynyl groups having 2 to 12 carbon atoms; cycloalkyl
groups; aralkyl groups; alkylaryl groups; and aryl groups.
The organic moiety R.sup.8 may be substituted or unsubstituted and may be
straight chain, branched or cyclic, saturated, unsaturated or aromatic.
Examples of such organic moieties include C.sub.1 -C.sub.8 alkyl moieties,
C.sub.2 -C.sub.8 alkenyl moieties, C.sub.2 -C.sub.8 alkynyl moieties,
C.sub.3 -C.sub.12 cycloaliphatic moieties, aryl moieties such as phenyl
and substituted phenyl and aralkyl moieties such as benzyl, methylbenzyl
and phenylethyl. Other organic moieties include substituted hydrocarbon
moieties, such as halo (e.g., chloro-, fluoro- and bromo-substituted
hydrocarbons) and oxy- (e.g., alkoxy substituted hydrocarbons) substituted
hydrocarbon moieties. Preferred organic moieties are alkyl, alkenyl and
alkynyl moieties having from 1 to about 8 carbon atoms, and
halo-substituted derivatives thereof. Particularly preferred are alkyl
moieties of 4 to 6 carbon atoms.
In the cyanoacrylate monomer of formula (III), R.sup.3 is preferably an
alkyl group having 1-10 carbon atoms or a group having the formula
--AOR.sup.9, wherein A is a divalent straight or branched chain alkylene
or oxyalkylene moiety having 2-8 carbon atoms, and R.sup.9 is a straight
or branched alkyl moiety having 1-8 carbon atoms.
Examples of groups represented by the formula --AOR.sup.9 include
1-methoxy-2-propyl, 2-butoxy ethyl, isopropoxy ethyl, 2-methoxy ethyl, and
2-ethoxy ethyl.
The preferred alpha-cyanoacrylate monomers used in this invention are
2-octyl cyanoacrylate, dodecyl cyanoacrylate, 2-ethylhexyl cyanoacrylate,
butyl cyanoacrylate, methyl cyanoacrylate, 3-methoxybutyl cyanoacrylate,
2-butoxyethyl cyanoacrylate, 2-isopropoxyethyl cyanoacrylate, or
1-methoxy-2-propyl cyanoacrylate.
The alpha-cyanoacrylates of formula (III) can be prepared according to
methods known in the art. Reference is made, for example, to U.S. Pat.
Nos. 2,721,858 and 3,254,111, each of which is hereby incorporated by
reference herein. For example, the alpha cyanoacrylates can be prepared by
reacting an alkyl cyanoacetate with formaldehyde in a non-aqueous organic
solvent and in the presence of a basic catalyst, followed by pyrolysis of
the anhydrous intermediate polymer in the presence of a polymerization
inhibitor. The alpha-cyanoacrylate monomers prepared with low moisture
content and essentially free of impurities are preferred for biomedical
use.
The alpha-cyanoacrylates of formula (III) wherein R.sup.3 is a group having
the formula --R.sup.4 --O--R.sup.5 --O--R.sup.6 can be prepared according
to the method disclosed in U.S. Pat. No. 4,364,876 to Kimura et al., which
is hereby incorporated by reference herein. In the Kimura et al. method,
the alpha-cyanoacrylates are prepared by producing a cyanoacetate by
esterifying cyanoacetic acid with an alcohol or by transesterifying an
alkyl cyanoacetate and an alcohol; condensing the cyanoacetate and
formaldehyde or para-formaldehyde in the presence of a catalyst at a molar
ratio of 0.5-1.5:1, preferably 0.8-1.2:1, to obtain a condensate;
depolymerizing the condensation reaction mixture either directly or after
removal of the condensation catalyst to yield crude cyanoacrylate; and
distilling the crude cyanoacrylate to form a high purity cyanoacrylate.
The alpha-cyanoacrylates of formula (III) wherein R.sup.3 is a group having
the formula
##STR5##
can be prepared according to the procedure described in U.S. Pat. No.
3,995,641 to Kronenthal et al., which is hereby incorporated by reference
herein. In the Kronenthal et al. method, such alpha-cyanoacrylate monomers
are prepared by reacting an alkyl ester of an alpha-cyanoacrylic acid with
a cyclic 1,3-diene to form a Diels-Alder adduct which is then subjected to
alkaline hydrolysis followed by acidification to form the corresponding
alpha-cyanoacrylic acid adduct. The alpha-cyanoacrylic acid adduct is
preferably esterified by an alkyl bromoacetate to yield the corresponding
carbalkoxymethyl alpha-cyanoacrylate adduct. Alternatively, the
alpha-cyanoacrylic acid adduct may be converted to the alpha-cyanoacrylyl
halide adduct by reaction with thionyl chloride. The alpha-cyanoacrylyl
halide adduct is then reacted with an alkyl hydroxyacetate or a methyl
substituted alkyl hydroxyacetate to yield the corresponding
carbalkoxymethyl alpha-cyanoacrylate adduct or carbalkoxy alkyl
alpha-cyanoacrylate adduct, respectively. The cyclic 1,3-diene blocking
group is finally removed and the carbalkoxy methyl alpha-cyanoacrylate
adduct or the carbalkoxy alkyl alpha-cyanoacrylate adduct is converted
into the corresponding carbalkoxy alkyl alpha-cyanoacrylate by heating the
adduct in the presence of a slight deficit of maleic anhydride.
Examples of monomers of formula (III) include cyanopentadienoates and
alpha-cyanoacrylates of the formula:
##STR6##
wherein Z is --CH.dbd.CH.sub.2 and R.sup.3 is as defined above. The
monomers of formula (IV) wherein R.sup.3 is an alkyl group of 1-10 carbon
atoms, i.e., the 2-cyanopenta-2,4-dienoic acid esters, can be prepared by
reacting an appropriate 2-cyanoacetate with acrolein in the presence of a
catalyst such as zinc chloride. This method of preparing
2-cyanopenta-2,4-dienoic acid esters is disclosed, for example, in U.S.
Pat. No. 3,554,990, which is hereby incorporated by reference herein.
Preferred monomers are alkyl alpha-cyanoacrylates and more preferably octyl
alpha-cyanoacrylates, especially 2-octyl alpha-cyanoacrylate. Monomers
utilized in the present application should be very pure and contain few
impurities (e.g., surgical grade).
Compositions of the present invention may include at least one plasticizing
agent that imparts flexibility to the polymerized monomer formed on the
wound or incision. The plasticizing agent preferably contains little or no
moisture and should not significantly affect the polymerization of the
monomer.
Other compositions are exemplified by U.S. Pat. Nos. 5,259,835 and
5,328,687 and U.S. patent applications Ser. Nos. 08/609,921, 08/714,288,
08/909,845, 08/755,007, 08/920,876, and 08/488,411, all incorporated by
reference herein in their entirety.
Examples of suitable plasticizers include acetyl tributyl citrate, dimethyl
sebacate, triethyl phosphate, tri(2-ethylhexyl)phosphate,
tri(p-cresyl)phosphate, glyceryl triacetate, glyceryl tributyrate, diethyl
sebacate, dioctyl adipate, isopropyl myristate, butyl stearate, lauric
acid, trioctyl trimellitate, dioctyl glutarate and mixtures thereof.
Preferred plasticizers are tributyl citrate and acetyl tributyl citrate.
In embodiments, suitable plasticizers include polymeric plasticizers, such
as polyethylene glycol (PEG) esters and capped PEG esters or ethers,
polyester glutarates and polyester adipates.
Compositions of the present invention may also include at least one acidic
stabilizing agent that inhibits polymerization. Such stabilizing agents
may also include mixtures of anionic stabilizing agents and radical
stabilizing agents.
Examples of suitable anionic stabilizing agents include, but are not
limited to, sultones (e.g.,
.alpha.-chloro-.alpha.-hydroxy-o-toluenesulfonic acid-.gamma.-sultone),
sulfur dioxide, sulfuric acid, sulfonic acid, sulfurous acid, lactone,
boron trifluoride, organic acids, alkyl sulfate, alkyl sulfite,
3-sulfolene, alkylsulfone, alkyl sulfoxide, mercaptan, and alkyl sulfide
and mixtures thereof. Preferable anionic stabilizing agents are acidic
stabilizing agents of organic acids such as acetic acid or phosphoric
acid. In embodiments, the amount of sulfur dioxide stabilizer is less than
100 ppm, preferably 5-75 ppm, and more preferably from about 20-50 ppm.
The amount of sultone and/or trifluoracetic acid is about 500-3000 ppm.
Examples of suitable radical stabilizing agents include hydroquinone,
hydroquinone monomethyl ether, catechol, pyrogallol, benzoquinone,
2-hydroxybenzoquinone, p-methoxy phenol, t-butyl catechol, butylated
hydroxy anisole, butylated hydroxy toluene, and t-butyl hydroquinone.
Suitable acidic stabilizing agents include those having aqueous pK.sub.a
ionization constants ranging from -12 to 7, preferably from about -3.5 to
about 6, and more preferably from about 2 to about 5.5. For example,
suitable acidic stabilizing agents include: hydrogen sulfide (pK.sub.a
7.0), carbonic acid (pK.sub.a 6.4), triacetylmethane (pK.sub.a 5.9),
acetic acid (pK.sub.a 4.8), benzoic acid (pK.sub.a 4.2), 2,4-dinitrophenol
(pK.sub.a 4.0), formic acid (pK.sub.a 3.7), nitrous acid (pK.sub.a 3.3),
hydrofluoric acid (pK.sub.a 3.2), chloroacetic acid (pK.sub.a 2.9),
phosphoric acid (pK.sub.a 2.2), dichloroacetic acid (pK.sub.a 1.3),
trichloroacetic acid (pK.sub.a 0.7), 2,4,6-trinitrophenol (picric acid)
(pK.sub.a 0.3), trifluoroacetic acid (pK.sub.a 0.2), sulfuric acid
(pK.sub.a - 3.0), and mixtures thereof.
When adding the above-mentioned acidic stabilizing agents to the adhesive
composition, the addition of plasticizing agents in amounts ranging from
about 0.5 wt. % to about 16 wt. %, preferably from about 3 wt. % to about
9 wt. %, and more preferably from about 5 wt. % to about 7 wt. % provides
increased film strength (e.g., toughness) of the polymerized monomer over
polymerized monomers having amounts of plasticizing agents and acidic
stabilizing agents outside of the above ranges.
The concentration of the acidic stabilizing agents utilized may vary
depending on the strength of the acid. For example, when using acetic
acid, a concentration of 80-200 ppm (wt/wt), preferably 90-180 ppm
(wt/wt), and more preferably 100-150 ppm (wt/wt) may be utilized. When
using a stronger acid such as phosphoric acid, a concentration range of
20-80 ppm (wt/wt), preferably, 30-70 ppm (wt/wt) and more preferably 40-60
ppm (wt/wt) may be utilized. In embodiments, the amount of trifluoroacetic
acid is about 100 to 3000 ppm, preferably 500-1500 ppm. In other
embodiments, the amount of phosphoric acid is about 10-200 ppm, preferably
about 50-150 ppm, and more preferably about 75-125 ppm.
Other compositions are exemplified by U.S. Pat. Nos. 5,624,669, 5,582,834,
5,575,997, 5,514,371, 5,514,372, 5,259,835 and 5,328,687, incorporated by
reference herein in their entirety. The compositions of the present
invention may also include at least one biocompatible agent effective to
reduce active formaldehyde concentration levels produced during in vivo
biodegradation of the polymer (also referred to herein as "formaldehyde
concentration reducing agents"). Preferably, this component is a
formaldehyde scavenger compound. Examples of formaldehyde scavenger
compounds useful in this invention include sulfites; bisulfites; mixtures
of sulfites and bisulfites; ammonium sulfite salts; amines; amides;
imides; nitriles; carbamates; alcohols; mercaptans; proteins; mixtures of
amines, amides, and proteins; active methylene compounds such as cyclic
ketones and compounds having a b-dicarbonyl group; and heterocyclic ring
compounds free of a carbonyl group and containing an NH group, with the
ring made up of nitrogen or carbon atoms, the ring being unsaturated or,
when fused to a phenyl group, being unsaturated or saturated, and the NH
group being bonded to a carbon or a nitrogen atom, which atom is directly
bonded by a double bond to another carbon or nitrogen atom.
Bisulfites and sulfites useful as the formaldehyde scavenger compound in
this invention include alkali metal salts such as lithium, sodium and
potassium salts, and ammonium salts, for example, sodium bisulfite,
potassium bisulfite, lithium bisulfite, ammonium bisulfite, sodium
sulfite, potassium sulfite, lithium sulfite, ammonium sulfite, and the
like.
Examples of amines useful in this invention include the aliphatic and
aromatic amines such as, for example, aniline, benzidine, aminopyrimidine,
toluene-diamine, triethylenediamine, diphenylamine, diaminodiphenylamine,
hydrazines and hydrazide.
Suitable proteins include collagen, gelatin, casein, soybean protein,
vegetable protein, keratin and glue. The preferred protein for use in this
invention is casein.
Suitable amides for use in this invention include urea, cyanamide,
acrylamide, benzamide, and acetamide. Urea is a preferred amide.
Suitable alcohols include phenols, 1,4-butanediol, d-sorbitol, and
polyvinyl alcohol.
Examples of suitable compounds having a b-dicarbonyl group include malonic
acid, acetylacetone, ethylacetone, acetate, malonamide, diethylmalonate or
another malonic ester.
Preferred cyclic ketones for use in this invention include cyclohexanone or
cyclopentanone.
Examples of suitable heterocyclic compounds for use as the formaldehyde
scavenger in this invention are disclosed, for example, in U.S. Pat. No.
4,127,382 (Perry) which is hereby incorporated by reference herein. Such
heterocyclic compounds include, for example, benzimidazole, 5-methyl
benzimidazole, 2-methylbenzimidazole, indole, pyrrole, 1,2,4-triazole,
indoline, benzotriazole, indoline, and the like.
A preferred formaldehyde scavenger for use in this invention is sodium
bisulfite.
In practicing the present invention, the formaldehyde concentration
reducing agent, e.g., formaldehyde scavenger compound, is added in an
effective amount to the cyanoacrylate. The "effective amount" is that
amount sufficient to reduce the amount of formaldehyde generated during
subsequent in vivo biodegradation of the polymerized cyanoacrylate. This
amount will depend on the type of active formaldehyde concentration
reducing agent, and can be readily determined without undue
experimentation by those skilled in the art.
The formaldehyde concentration reducing agent may be used in this invention
in either free form or in microencapsulated form. Other compositions are
exemplified by U.S. patent application Ser. No. 08/714,288, incorporated
by reference herein in their entirety.
When microencapsulated, the formaldehyde concentration reducing agent is
released from the microcapsule continuously over a period of time during
the in vivo biodegradation of the cyanoacrylate polymer.
For purposes of this invention, the microencapsulated form of the
formaldehyde concentration reducing agent is preferred because this
embodiment prevents or substantially reduces polymerization of the
cyanoacrylate monomer by the formaldehyde concentration reducing agent,
which increases shelf-life and facilitates handling of the monomer
composition during use.
Microencapsulation of the formaldehyde scavenger can be achieved by many
known microencapsulation techniques. For example, microencapsulation can
be carried out by dissolving a coating polymer in a volatile solvent,
e.g., methylene chloride, to a polymer concentration of about 6% by
weight; adding a formaldehyde scavenger compound in particulate form to
the coating polymer/solvent solution under agitation to yield a scavenger
concentration of 18% by weight; slowly adding a surfactant-containing
mineral oil solution to the polymer solution under rapid agitation;
allowing the volatile solvent to evaporate under agitation; removing the
agitator; separating the solids from the mineral oil; and washing and
drying the microparticles. The size of the microparticles will range from
about 0.001 to about 1000 microns.
The coating polymer for microencapsulating the formaldehyde concentration
reducing agent should be polymers which undergo in vivo bioerosion,
preferably at rates similar to or greater than the cyanoacrylate polymer
formed by the monomer, and should have low inherent moisture content. Such
"bioerosion" can occur as a result of the physical or chemical breakdown
of the encapsulating material, for example, by the encapsulating material
passing from solid to solute in the presence of body fluids, or by
biodegradation of the encapsulating material by agents present in the
body.
Examples of coating materials which can be used to microencapsulate the
formaldehyde concentration reducing agent include polyesters, such as
polyglycolic acid, polylactic acid, poly-1,4-dioxa-2-one, polyoxaltes,
polycarbonates, copolymers of polyglycolic acid and polylactic acid,
polycaprolactone, poly-b-hydroxybutyrate, copolymers of
epsilon-caprolactone and delta-valerolactone, copolymers of
epsilon-caprolactone and DL-dilactide, and polyester hydrogels;
polyvinylpyrrolidone; polyamides; gelatin; albumin; proteins; collagen;
poly(orthoesters); poly(anhydrides); poly(alkyl-2-cyanoacrylates);
poly(dihydropyrans); poly(acetals); poly(phosphazenes); poly(urethanes);
poly(dioxinones); cellulose; and starches.
Examples of the surfactant which can be added to the mineral oil include
those commercially available under the designations Triton x-100, Tween 20
and Tween 80.
The composition of this invention may further contain one or more adjuvant
substances, such as thickening agents, medicaments, or the like, to
improve the medical utility of the monomer for particular medical
applications.
Suitable thickeners include, for example, polycyanoacrylates, polylactic
acid, polyglycolic acid, lactic-glycolic acid copolymers,
polycaprolactone, lactic acid-caprolactone copolymers,
poly-3-hydroxybutyric acid, polyorthoesters, polyalkyl acrylates,
copolymers of alkylacrylate and vinyl acetate, polyalkyl methacrylates,
and copolymers of alkyl methacrylates and butadiene. Examples of alkyl
methylacrylates and acrylates are poly(2-ethylhexyl methacrylate) and
poly(2-ethylhexyl acrylate), also poly(butylmethacrylate) and
poly(butylacrylate), also copolymers of various acrylate and methacrylate
monomers, such as poly(butyl methacrylate-co-methylacrylate).
To improve the cohesive strength of adhesives formed from the compositions
of this invention, difunctional monomeric cross-linking agents may be
added to the monomer compositions of this invention. Such crosslinking
agents are known. Reference is made, for example, to U.S. Pat. No.
3,940,362 to Overhults, which is hereby incorporated by reference herein.
Examples of suitable crosslinking agents include alkyl
bis(2-cyanoacrylates), triallyl isocyanurates, alkylene diacrylates,
alkylene dimethacrylates, trimethylol propane triacrylate, and alkyl
bis(2-cyanoacrylates). A catalytic amount of an amine activated free
radical initiator may be added to initiate polymerization of the
cyanoacrylate monomer/crosslinking agent blend.
The compositions of this invention may further contain fibrous
reinforcement and colorants, i.e., dyes and pigments. Examples of suitable
fibrous reinforcement include PGA microfibrils, collagen microfibrils,
cellulosic microfibrils, and olefinic microfibrils. Examples of suitable
colorants include 1-hydroxy-4-[4-methylphenyl-amino]-9,10 anthracenedione
(D+C violet No. 2); disodium salt of
6-hydroxy-5-[(4-sulfophenyl)axo]-2-naphthalene-sulfonic acid (FD+C Yellow
No. 6); 9-(o-carboxyphenyl)-6-hydroxy-2,4,5,7-tetraiodo-3H-xanthen-3-one,
disodium salt, monohydrate (FD+C Red No. 3);
2-(1,3-dihydro-3-oxo-5-sulfo-2H-indol-2-ylidene)-2,3-dihydro-3-oxo-1H-indo
le-5-sulfonic acid disodium salt (FD+C Blue No. 2); and [phthalocyaninato
(2-)] copper.
Depending on the particular requirements of the user, the adhesive
compositions of this invention can be applied by known means such as with
a swab, glass stirring rod, sterile brush or medicine dropper. However, in
many situations a spray dispensing package is preferred in which the
adhesive composition is in solution with a compatible anhydrous
propellant. Other modes of application are exemplified in U.S. patent
application Ser. No. 08/488,411, incorporated by reference herein in its
entirety.
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